The levels of tetrahydracannibinol or “THC,” the active chemical in marijuana that produces the altered states of consciousness, have reached a 30-year high, according to a press release published by the Office of National Drug Control Policy.

University of Mississippi’s Potency Monitoring Project analyzed 62,797 cannabis samples, 1,302 hashish samples and 468 hash oil samples seized by law enforcement agencies in 48 states since 1975.

The study found that the average amount of THC was 9.6 percent in 2007, compared with 8.75 percent the previous year and just fewer than 4 percent in 1983.

The finding highlights the need of getting marijuana off the list of harmless drugs because it might cause psychological, cognitive and respiratory problems, as well as dependency on other drugs, such as cocaine and heroin, the Office of National Drug Control Policy noted.

The agency’s director, John Walters, said “marijuana potency has grown steeply over the past decade, with serious implications in particular for young people,” CNN quotes him.

The marijuana’s potency was attributed to sophisticated growing techniques used by drug traffickers in the U.S. and Canada.

There are more than 28 million marijuana users in the United States and approximately 300 million around the world. Marijuana’s side effects may not be visible “today,” but they will sure be visible “tomorrow” on its users’ health.